Method for low temperature catalytic production of hydrogen

ABSTRACT

The invention provides a process for the catalytic production of a hydrogen feed by exposing a hydrogen feed to a catalyst which promotes a base-catalyzed water-gas-shift reaction in a liquid phase. The hydrogen feed can be provided by any process known in the art of making hydrogen gas. It is preferably provided by a process that can produce a hydrogen feed for use in proton exchange membrane fuel cells. The step of exposing the hydrogen feed takes place preferably from about 80° C. to about 150° C.

[0001] This invention was made with Government support under contractnumber DE-AC02-98CH10886, awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a process for the production ofhydrogen. More specifically, this invention relates to a catalyticprocess for the production of hydrogen at low temperatures for use inmethanol or proton exchange membrane fuel cells.

[0004] 2. Description of the Related Art

[0005] Fuel cells combine hydrogen and oxygen without combustion to formwater and to produce direct current electric power. The process can bedescribed as electrolysis in reverse. Fuel cells have been pursued as asource of power for transportation because of their high energyefficiency, their potential for fuel flexibility, and their extremelylow emissions. Fuel cells have potential for stationary and vehicularpower applications; however, the commercial viability of fuel cells forpower generation in stationary and transportation applications dependsupon solving a number of manufacturing, cost, and durability problems.

[0006] The most promising fuel cells for widespread transportation useare Proton Exchange Membrane (PEM) fuel cells. PEM fuel cells operate atlow temperatures, produce fast transient response, and have relativelyhigh energy density compared to other fuel cell technologies. Any fuelcell design must: (a) allow for supply of the reactants (typicallyhydrogen and oxygen); (b) allow for mass transport of product (water)and inert gases (nitrogen and carbon dioxide from air), and (c) provideelectrodes to support catalyst, collect electrical charge, and dissipateheat.

[0007] Proton exchange membranes (PEM) fuel cells that typically utilizePt on carbon support (Pt/C) as anode electrocatalyst operate at a lowertemperature of 80° C. hold commercial promise. For methanol fuel cells,H₂ feed can be produced via one of the following reactions:

CH₃OH+H₂O→3H₂+CO₂ ΔH=+49.4 kJ.mol ⁻¹   (1)

CH₃OH+½O_(2→)2H₂+CO₂ ΔH=−192.2 kJ.mol ⁻¹   (2)

[0008] Steam reforming of methanol in Reaction 1 is carried out attemperatures greater than 280° C. over supported Cu/Zn catalysts asdescribed by Velu, Suzuki and Osaki in Chem. Communications, No.23,2341-2342 (1999). Partial oxidation of methanol in Reaction 2 is alsofeasible and the reaction is exothermic. See Cubeiro and Fierro inJournal of Catalysts 179, 150-162 (1998). However, a shortcoming of theabove process is that the hydrogen feed produced in this manner has ahigh content of carbon monoxide (CO). It is known that Pt is readilypoisoned by CO. Therefore, a major challenge to the commercializing ofthe PEM fuel cell technology is to produce H₂ that is essentially freeof CO. Several catalysts of the type Pt—Ru/C or Pt—Mo/C, have beenformulated to increase CO tolerance of the Pt catalyst as discussed in areview article by Mukerjee, et al., Electrochemical and Solid-StateLetters. 2(1) 12-15 (1999). But even at a CO content of 100 ppm in theH₂ feed, severe catalyst poisoning is observed.

[0009] H₂ produced via Reaction 1 or 2 contains more than 100 ppm CO.Currently, a catalytic water-gas-shift (WGS) step as illustrated byReaction 3 is added to remove CO to acceptable levels (<20 ppm) prior tofeeding H₂ to the fuel cell.

CO_((g))+H₂O_((g))

H_(2(g))+CO_(2(g)) ΔH=−39.4 kJ.mol ⁻¹   (3)

[0010] Reaction 3 is typically catalyzed by promoted iron oxides attemperatures greater than 300° C. as discussed by C. L. Thomas, in“Catalytic Processes and Proven Catalysts”, Academic Press, New York,1970. As a result, such high temperature pretreatment unnecessarily addscost to the process. Moreover, in the gas phase, Reaction 3 is in anequilibrium that invariably leaves some CO in the product H₂ stream.

[0011] Accordingly, there is still a need in the art of PEM fuel cellsto utilize hydrogen that is essentially free of carbon monoxide.Additionally, there is also a need to provide the hydrogen gas in aprocess that is conducted at low temperature by using inexpensive andsimple methods.

OBJECTS OF THE INVENTION

[0012] It is, therefore, an object of the present invention to providean improved process for the production of hydrogen gas.

[0013] It is a further object of the invention to provide a catalyticprocess for the production of hydrogen gas which contains reduced carbonmonoxide content.

SUMMARY OF THE INVENTION

[0014] The present invention, which addresses the needs of the priorart, provides a process for the catalytic production of a hydrogen feedby exposing a hydrogen feed to a catalyst which promotes awater-gas-shift reaction in a liquid phase. The hydrogen feed can beprovided by any process known in the art of making hydrogen gas. It ispreferably provided by steam reforming or oxidation of methanol or byany other process that can produce a hydrogen feed for use in protonexchange membrane fuel cells. The step of exposing the hydrogen feedtakes place preferably from about 80° C. to about 150° C. Formate isformed when the water-gas-shift reaction is base catalyzed.

[0015] The catalyst used in the process of the present invention can beselected from homogenous transition metal complexes. The transitionmetal of the complex is preferably a metal selected from Group V III Aof the periodic table, including, for example, Fe, Co, Ni, Ru, Rh, Pd,Os, Ir, Pt and Cu. The transition metal can be coupled to at least one Ndonor ligand such as 2,2′-dipyridyl(BIPY), sodium salt ofethylenediamine tetraacetic acid, ethylenediamine, 1,10-phenanthroline,4,4′-dipyridyl, 1,4,8,11-tetraazacyclotetradecane(CYCLAM),N,N-Bis(2-hydroxybenzl)ethylenediamine H₄(SALEN), or mixtures thereof.The catalytic process of the invention is carried out preferably in ahighly basic liquid phase such as provided by water, methanol, glyme,polyglycol, other alcohols from C₂ to C₁₀ or ethers from C₂ to C₁₀ andmixtures thereof. The liquid phase is made basic by adding bases in anamount sufficient to promote formate formation The pH of the liquidphase is preferably greater than 8.

[0016] As a result of the process of the present invention, a newintegrated system that operates at low temperatures is provided. Thesystem consists of two steps: 1) catalyzed methanol decomposition at atemperature of less than 150° C. to produce 1 mol CO and 2 mol H₂followed by, 2) fast and complete CO conversion to CO₂ with concomitantproduction of 1 mol of H₂ via the present invention. The presentintegrated system thus produces 3 mol H₂/mol methanol at low temperatureof less than 150° C. compared to schemes for methanol fuel cell systemsthat are under development.

[0017] Other improvements which the present invention provides over theprior art will be identified as a result of the following descriptionwhich set forth the preferred embodiments of the present invention. Thedescription is not in any way intended to limit the scope of the presentinvention, but rather only to provide the working example of the presentpreferred embodiments. The scope of the present invention will bepointed out in the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is a process for the catalytic productionof hydrogen feed at low temperatures for use in proton exchange membranefuel cells. More specifically, the gaseous feed formed by the process ofthe present invention is hydrogen rich and contains very low levels ofcarbon monoxide.

[0019] In the process of the present invention a hydrogen feed can beformed by any process known in the art. A hydrogen feed is preferablyformed by steam reforming or oxidation of methanol, methane or biomass.Hydrogen feed can also be obtained from gasification of coal and othercarbonaceous materials including, without limitations, wastes of organicmaterials, plastics, farm, wood chips and other industrial wastes. Onceformed, the hydrogen feed is exposed to a catalytic liquid phasehomogeneous systems to achieve a water-gas-shift reaction for CO removalto levels less than 50 ppm. In the reaction know as water-gas-shift,water is reacted with carbon monoxide to yield hydrogen and carbondioxide. This reaction is shown below:

CO_((g))+H₂O₍₁₎

H_(2(g))+CO_(2(g)) ΔH=+2.8 kJ.mol ⁻¹   (3A)

[0020] This reaction operates at a low temperature of less than 150° C.CO is dissolved in the liquid phase and reacts with water on ahomogenous catalytic system to produce H₂ and CO₂.

[0021] For application to PEM fuel cells, two requirements must be met.These are: 1) the reaction preferably operates at a lower temperature offrom about 80° C. to about 150° C.: and 2) CO removal to less than 50ppm is achieved with fast reaction rates. In studies reported inliterature, the mechanism of homogeneously catalyzed WGS reaction hasbeen established. For example, in base-catalyzed WGS reactions, formateion is invoked as an intermediate as shown in Reactions 4 and 5 below:

CO+⁻OH→HCO₂ ⁻  (4)

HCO₂ ⁻+H₂O→H₂+CO₂+⁻OH   (5)

[0022] The sum of Reactions 4 and 5 is the WGS reaction (3) above. Thus,catalyzed formate decomposition is also a measure of WGS activity of acatalyst.

[0023] The advantage of the present invention is provided by thethermodynamic advantage of Reaction (3A) as opposed to Reaction (3)above. In the prior art the WGS reactions are in the gas phase. As aresult of a negative enthalpy, Reaction (3) tends to go backwards toproduce large amounts of CO. In the present invention, the mechanismillustrated in Reaction (3A) indicates that the reaction goes only inforward direction because in the liquid phase the homogenous catalystreacts with CO and then picks up water to form CO₂. That is why by usinga catalytic liquid phase homogenous system almost 100% of CO isconverted to CO₂

[0024] Commercially available from Aldrich Corp. and several othervendors, several metals (heterogeneous) and metal complexes(homogeneous) have been employed as catalysts useful in the presentinvention. Under basic conditions, at pH greater than 8, formateformation is facilitated as shown in Equation 6 below:

AM-OH+CO→AM-HCO₂   (6)

(AM=Li, Na, K, Cs)

[0025] Thus, Equation 7 is a part of the WGS catalytic cycle:

AM-HCO₂+H₂O→AM-OH+H₂+CO₂   (7)

[0026] Useful sources of formate include formate salts of lithium,sodium, potassium and cesium, all readily available commercially orthese materials can be conveniently synthesized in batches in thelaboratory according to procedures well known in the art. Useful basesfor inclusion in the liquid phase include, without limitation,hydroxides, alkoxides, bicarbonates of lithium, sodium, potassium andcesium. Alkyl amines wherein the alkyl group is from C₁-C₄ are alsouseful bases for the purposes of the present invention. A preferred baseis potassium hydroxide.

[0027] In the present invention, commercially available transition metalcomplexes, based on Ru, Ni, Rh, Pt, Co, Fe, Pd, Os, Ir, Cu metals inmethanol/H₂O solvent mixture are employed. Useful transition metalcomplexes for this invention are easily commercially available andinclude without limitation RuCl₃.xH₂O, Ru₃(CO)₁₂, NiCl₂.6H₂O,RhCl₃.3H₂O, CoCl₂, K₂PtCl₄, FeCl₂, Ru(CO)₅, Ni(CO)₄, Rh₆(CO)₁₆,Co₂(CO)₈, [Pt(CO)(Cl₂)]₂ and mixtures thereof. For RuCl₃.xH₂O, x is aninteger between 0 to 3.

[0028] A preferred catalyst is formed by dissolving RuCl₃xH₂O with awater-soluble ligand such as 2,2′-dipyridyl(BIPY) as manufactured byAldrich, a commercial vendor. An organic solvent may be added such asmethanol, ethanol and the like. Listed in Table 1 below are experimentsthat show the activity pattern of various catalysts useful in formatedecomposition.

[0029] The experiments summarized in Table 1 were obtained by catalyzing50 mmol of KHCO₂ in 130 ml of a solvent mixture of 5% H₂O/10%methanol/85% triglyme, all placed in a 0.5L AE Zipperclave batch reactorat a temperature of 120° C. and a pressure of 1.4 MPa. TABLEDecomposition of Inorganic Formates Catalyzed by Metal Complexes FinalGas Analysis H₂ CO Time % KHCO₂ Run No. Catalyst (mmol) mmol minutesDecomposition 1 — 1 — 140 2 2 RuCl₃ · x H₂O/- 35 — 80 70 (3) 3NiCL₂.₆H₂O/BIPY 5 — 120 10 (3) (3) 4 RuCl₃ · x H₂O/BIPY 47 — <5 94 (3)(3) 5 RhCl₃.3H₂O/BIPY 50 — <30 80 (3) (3) 6 CoCl₂/BIPY 2 — 55 4 (3) (3)7 K₃PtCl₄/BIPY 43 — <10 86 (3) (3) 8 FeCl₂/BIPY 3 — 30 6 (3) (3) 9 RuCl₃· x H₂O/BIPY 50 — <2 100* (3) (3) *(T = 140° C.)

[0030] From Table 1 above, it is apparent that the preferred catalystsystem contained Ru and N-donor ligands. N-donor ligands useful in thecatalyst system of the present invention include but not limited to are2,2′-dipyridyl(BIPY), sodium salt of ethylenediamine tetraacetic acid,ethylenediamine, 1,10-phenanthroline, 4,4′-dipyridyl,1,4,8,11-tetraazacyclotetradecane(CYCLAM),N,N-Bis(2-hydroxybenzyl)ethylenediamine H₄(SALEN).

[0031] The solvent system typically employed for the homogenouscatalysts useful in the present on is an organic and/or aqueous solventsuch as methanol, ethanol, other higher alcohols, glymes, polyglycol,water and mixtures thereof. H₂ is produced with extremely fast reactionrates. Turnover numbers as high as 8 mol H₂/mol Ru/min have beenobtained. When the catalyst system also contains N-donor ligandsturnover numbers are enhanced and can vary from about 0.1 to about 12mol H₂/mol metal/min. Applying the process of the present invention to agaseous stream of CO, H₂O and H₂ and CH₃OH results in removal of CO tovery low levels. For example, levels of carbon monoxide well below 50ppm, and preferably less than 20 ppm can be achieved.

[0032] In the examples that follow, essentially complete formatedecomposition as well as CO to CO₂ oxidation with H₂O is demonstrated.Such a system allows removal of CO to well below the 50 ppm level from agas stream containing CO, H₂O, H₂, CH₃OH.

EXAMPLES

[0033] The examples below further illustrate the various features of theinvention and are not intended in any way to limit the scope of theinvention which is defined in the appended claims. All materials used inthe examples of the present invention are readily commerciallyavailable. Gas analysis data were collected on Gow-Mac 550 gaschromatographs, operating in the thermal conductivity detector (TCD)mode, as follows: H₂ was analyzed on a 5 Å molecular sieve columnmanufactured by Linde Corp. (6 feet×⅛ inch) with N₂ as the carrier gas,CO was also analyzed on a 5 Å molecular sieve column manufactured byLinde Corp. (8 feet×⅛ inch) with He as the carrier gas and CO₂ wasanalyzed on Carboxen-1000 column (5 feet×⅛ inch) gas with He as thecarrier gas.

Example 1

[0034] This example illustrates the catalytic activity of rutheniumtrichloride for potassium formate (KHCO₂) decomposition. A deep redsolution resulted on adding 3 mmol RuCl₃.xH₂O to 130 ml of 85%triglyme/10% MeOH/5% H₂O solvent mixture. The red solution and 50 mmolof KHCO₂ were loaded into an AE Zipperclave batch unit consisting of a0.5 L pressure vessel, as manufactured by Autoclave Engineers (AE). Thevessel was pressurized with 1.4 MPa N₂ and heated to 120° C. Thepressure increased with time at a constant temperature of 120° C.Heating was continued for 80 minutes until a constant temperature wasattained indicating that gas evolution of mainly CO₂ and H₂ from formatedecomposition had ceased. On cooling the vessel, a net pressure increaseof 0.22 MPa was noted.

[0035] The final gas analysis at room temperature was as follows:H₂=10.8%, CO₂=4.1%, CO less than 50 ppm. N₂ was calculated by differencewith an accurate overall mass balance. The CO value of less than 50 ppmrepresents the detection limit of the gas chromatograph operating inthat TCD mode. Equivalent amounts of 50 mmol each of H₂ and CO₂ wereexpected from the complete decomposition of 50 mmol KHCO₂. The measuredH₂ concentration of 35 mmol was equivalent to 70% KHCO₂ decomposition.The interaction of produced CO₂ with dissolved base such as KOH in thesolution resulted in the CO₂ value that was at 11 mmol lower thanexpected. These data established that the decomposition reaction wascatalytic with respect to Ru because turnover numbers as high as 12 molH₂/mol Ru/min were obtained.

Example 2—Comparative

[0036] Example 1 was repeated without adding the catalyst RuCl₃.xH_(2O).After 140 minutes at 120° C. the gas phase was analyzed as follows:H₂=0.8%, CO₂=1.1%, CO=0.3%. 1 mmol of H₂ produced was equivalent to 2%KHCO₂ decomposition. This run established that the Ru catalyst wasnecessary to achieve KHCO₂ decomposition.

Example 3

[0037] Example 1 was repeated using as the catalyst 1 mmol RuCl₃.xH₂O inthe absence of H₂O and the solvent mixture was adjusted to 90%triglyme/10% MeOH. The initial 1.40 MPa N₂ pressure stabilized in 70minutes at 2.46 MPa. The final analysis yielded H₂=6.0%, CO₂=1.4%, CO<50ppm. From the measured concentration of H₂, the KHCO₂ decomposition wascalculated to be about 30%. The data showed that the absence of H₂Oretarded the decomposition reaction.

Example 4

[0038] In this example, the effect of the nature of the alkali metalassociated with the formate was evaluated. The experimental conditionswere the same as in Example 1 except that KHCO₂ was replaced with anequivalent amount of NaHCO₂ and only 1 mmol RuCl₃.xH₂O was used. After188 minutes at 120° C., the final gas analysis was as follows: H₂=9.5%,CO₂=4.5% CO=0.1%. NaHCO₂ decomposition was calculated to be about 46%.

Example 5

[0039] In this example, the conditions were kept constant as in Example1 except that RuCl₃.x H₂O was replaced with 1 mmol Ru₃(CO)₁₂ whichprovides 3 mmol Ru equivalent. The final gas phase contained 9 mmol H₂,3 mmol CO₂, 1 mmol CO. The produced H₂ corresponded to about 18% KHCO₂decomposition.

Example 6

[0040] In this example, the effect of an added ligand was evaluated.Example 1 was repeated in the presence of 2,2′-dipyridyl. The initial1.4 MPa pressure stabilized at 2.54 MPa in less than 5 minutes at 120°C. The gas analysis was as follows: H₂=15.4%, CO₂=1.7%, CO less than 50ppm. The measured H₂ concentration of 47 mmol corresponded to 94% KHCO₂decomposition. These data showed that the reaction was catalyzed by bothRu as well as the ligand. Sixteen turnover numbers each were obtained.

Example 7

[0041] Example 6 was repeated except that, in the solvent mixture,triglyme was replaced with polyglycol (Peg-400). The initial pressure of1.4 MPa at room temperature increased to 2.39 MPa at 120° C. Thepressure was further increased to 2.53 MPa in 20 minutes and thenremained constant. The final gas analysis was as follows: H₂=14.5%,CO₂=2.9%, CO less than 50 ppm. The measured H₂ concentration of 43 mmolindicated that about 86% KHCO₂ decomposed.

[0042] In the above examples, formate was decomposed to hydrogen, carbondioxide and less than 50 ppm of carbon monoxide in the presence ofruthenium metal complexes. Especially (rood results were obtained whenthe metal complexes were in the presence of 2.2′-bipyridyl. Examples8-20 demonstrate that the decomposition of KHCO₂ can be catalyzed bytransition metal complexes other than Ru.

Example 8

[0043] Under the conditions of Example 1, RuCl₃.xH₂O was replaced withNiCl₂.6H₂O. The lime green solution of the Ni complex was mixed withKHCO₂ and the solution was heated to 120° C. under 1.4 MPa N₂. At 120minutes at 120° C., the pressure was constant at 2.25 MPa indicatingthat any H₂ production from KHCO₂ decomposition had ceased. Gas analysisindicated that the gas-phase H₂ value was constant. The final roomtemperature gas analysis was as follows: H₂=1.8%, CO₂=1.6%, CO<0.01%.These results indicated that only 8% formate decomposed was achieved.

Example 9

[0044] Example 8 was repeated with NiCl₂.6H₂O in the presence of 3 mmolof 2,2′-dipyridyl. After 105 minutes at 120° C., the final valuecorresponded to 10% decomposition of formate. The results of thisexperiment indicate that the added ligand only marginally acceleratedthe decomposition reaction.

Example 10

[0045] Example 9 was repeated except that NiCl₂.6H₂O was replaced withFeCl₂. The solution was heated to 120° C. under 1.4 MPa N₂. After 120minutes at 120° C., the pressure was constant at 2.15 MPa. Gas analysisindicated that the gas-phase H₂ value was constant. The final roomtemperature gas analysis was as follows: H₂=0.9%, CO₂=0.6%, CO<0.01%.The measured H₂ yield indicated that only 6% formate decomposed.

Example 11

[0046] Example 9 was repeated except that NiCl₂.6H₂O was replaced with 3mmol Fe(CO)₅. After 30 minutes at 120° C., the pressure was constant at2.33 MPa. The final gas analysis was as follows: H₂=3.3%, CO₂=1.5%,CO=4.7%. The H₂ yield of 10 mmol corresponed to 20% KHCO₂ decompositionequivalent. The reaction also produced 16.5 mmol CO.

Example 12

[0047] Example 8 was repeated with 5 minol Fe(CO)₅ as the catalyst.After heating at 120° C. for 129 minutes, the final pressure wasconstant at 2.37 MPa. The final gas analysis was as follows: H₂=2.2%,CO₂=2.1%, CO=2.1%. The produced H₂ concentration of 6 mmol corresponedto 12% KHCO₂ decomposition equivalent. In this run, 5 mmol CO was alsoproduced as a gaseous product.

Example 13

[0048] In Example 8, NiCl₂.6H₂O was replaced with 3 mmol RhCl₃.3H₂O and3 mmol of 2,2′-dipyridyl ligand was added. After 30 minutes at 120° C.,the pressure stabilized at 2.43 MPa. The final gas analysis was:H₂=13.5%, CO₂=3.5%, CO<50 ppm. These results showed that 40 mmol H₂ wasproduced. The H₂ value corresponded to 80% KHCO₂ decompositionequivalent.

Example 14

[0049] Example 8 was repeated with 0.5 mmol Rh₆(CO)₁₆ which correspondedto 3 mmol Rh equivalent. After heating at 120° C. for 60 minutes, thefinal pressure was constant at 2.54 MPa. The final gas analysis was asfollows: H₂=15.1%, CO₂=2.6%, CO =0.17%). The produced H₂ value of 41mmol corresponded to about 82% KHCO₂ decomposition.

Example 15

[0050] Example 14 was repeated with Rh₆(CO)₁₆ in the presence of added 3mimol of 2,2′-dipyridyl ligand. The final pressure was constant at 2.40MPa after 110 minutes at 120° C. The final gas analysis was as follows:H₂=12.7%, CO₂=2.8%, CO<50 ppm. The produced H₂ value of 33 mmolcorresponded to about 66% KHCO₂ decomposition.

Example 16

[0051] Example 8 was repeated with 3 mmol of K₂PtCl₆ as the catalyst.The pressure stabilized at 2.52 MPa. after 25 minutes at 120° C. Thefinal gas analysis was as follows: H₂=16.0%, CO₂=3.2%, CO<50 ppm. Theformate decomposition was calculated to be about 87% from produced H₂concentration of 43.5 mmol.

Example 17

[0052] Example 16 was repeated with 3 mmol of 2,2′-dipyridyl ligandadded to K₂PtCl₆. The final constant pressure was recorded at 2.61 MPaafter 10 minutes at 120° C. The gas analysis was as follows: H₂=16.0%,CO₂=4.8%, CO<50 ppm. The formate decomposition was calculated to be 86%from the produced H₂ value of 43 mmol.

Example 18

[0053] Example 17 was repeated, however, K₂PtCl₆ was replaced with 3mmol of K₂PtCl₄. The final pressure stabilized at 2.57 MPa after 20minutes at 120° C. The gas analysis was as follows: H₂=16.9%, CO₂=3.1%,CO<50 ppm. H₂ was calculated to be 48 mmol that corresponed to about 96%formate decomposition.

Example 19

[0054] Example 8 was repeated after replacing NiCl₂.6H₂O with 3 mmolCoCl₂ in the presence of 3 mmol of 2,2′-dipyridyl ligand. The finalpressure was 2.08 MPa in 55 minutes at 120° C. The gas analysis was asfollows: H₂=0.7%, CO₂=0.6%. The H₂ value of 2 mmol corresponded to 4%KHCO₂ decomposition.

Example 20

[0055] Example 8 was repeated after replacing NiCl₂.6H₂O with 1.5 mmolCo₂(CO)₈ which represents 3 mmol Co equivalent and 3 mmol of added2,2′-dipyridyl ligand. The final pressure was 2.32 MPa in 150 minutes at120° C. From the gas analysis, based on 8 mmol H_(2,) KHCO₂decomposition was calculated to be about 16%.

[0056] Examples 21-25 illustrate the applicability of metal-catalyzedliquid-phase homogeneous systems to oxidize efficiently CO to CO₂ in agas stream containing a mixture of CO, H₂O. CH₃OH and CO₂.

Example 21

[0057] 3 mmol of RuCl₃.xH₂O, 3 mmol of 2,2′-dipyridyl, and 0.3 mmol ofKOH were dissolved in 130 mL 50% MeOH/50% H₂O solvent mixture. Theresulting deep red solution was loaded and sealed in a 0.5 L pressurevessel in the AE Zipperclave batch unit. The vessel was purged twicewith 50 psi CO, charged with 0.767 MPa CO and the gas phase of thevessel was analyzed to be 99.8% CO, with no H₂ detected. After heatingthe vessel, the pressure increased to 1.807 at 130° C. and remainedconstant. A gas sample taken at time, t=0, at 130° C. analyzed asfollows: H₂=97.8%, CO<0.005%. The gas-phase composition remainedconstant after the solution was cooled to room temperature. Fromequivalent added CO, a total of 120 mmol H₂ was produced. These datashowed that the reaction was catalytic both in RuCl₃.xH₂O as well as in2,2′-dipyridyl. Forty turnover numbers were obtained each for Ru and theligand.

Example 22

[0058] The final solution in Example 21 was heated to 140° C. and thenfurther charged with CO to 3.22 MPa. The gas analysis data as a functionof time at 140° C. is given below: Gas Analysis Time, min P_(T), MPa %CO % H₂ % CO₂ 0 3.17 * * * 5 3.22 13.0 77.5 * 16 2.80 3.4 87.0 * 23 3.091.12 81.9 * 35 3.23 0.22 83.1 * 45 3.33 0.083 84.0 * 90 3.38 0.014 84.38.4

[0059] The above data shows that a quick drop in the CO concentrationfrom 13.0% to 3.4% was observed after the first 16 minutes. Thereafter,the CO dropped from 3.4% to 0.014% in 90 mimnutes . The ratio of H₂produced to KOH was 0.71. These data illustrate that the reaction wasdependent on the KOH concentration.

Example 23

[0060] The example further confirms that the CO removal from the initialgas stream is dependent on KOH concentration. A dark brown solutionresulted on adding 3 mmol of RuCl₃.xH₂O 6 mmol of 2,2′-dipyridyl in 85%triglyme/10% MeOH/5% H₂O solvent mixture. 50 mmol of KHO was then addedto the dark brown solution. The base dissolved but the solution becamebiphasic. The biphasic solution was initially heated to 115° C. and thento 140° C. under 1.10 MPa syngas (H₂/CO=66%/34%). The gas analysis datais as follows: Gas Analysis Time, min T, ° C. P_(T), MPa % CO % H₂ % CO₂1 115 1.20 36.3 28.0 * 5 140 1.50 34.0 53.3 0.5 85 140 1.63 28.3 60.03.0

[0061] The above data shows that of the initial amount of 64 mmol CO (insyngas), 45 mmol remained unconverted after 85 minutes at 140° C. Inthis reaction, 20 mmol CO and 44 mmol H₂ were consumed to generateproducts, likely methanol, in addition to CO₂ and H₂.

Example 24

[0062] Example 21 was repeated with 3 mmol of RuCl₃.xH₂O, 3 mmol of2,2′-dipyridyl and 100 mmol KOH dissolved in 20% MeOH/20% H₂O/60%Peg-400 solvent mixture. The dark brown solution was heated to 140° C.under 1.10 MPa syngas (H₂/CO=66%/34%). After 3 minutes the gas analysiswas as follows: H₂=94.7%, CO=0.14%. The analysis after 27 minutes at140° C. was H₂=95.4%, CO<50 ppm. This data showed that the catalystwas: 1) effective in polyethylene glycol solvent, and 2) active in asolvent mixture containing high H₂O concentration.

Example 25

[0063] Example 21 was repeated after replacing KOH with 100 mmol ofKHCO₂. Thus, KHCO₂ served as a source of CO. The dark brown solution washeated to 140° C. under 0.67 MPa H₂. The pressure increased to 2.46 MPaat 140° C. and continued to increase to 3.06 MPa. After 11 minutes, lessthan 50 ppm CO was detected. The corresponding H₂ and CO₂ values were93.8% and 4.5% respectively.

Example 26

[0064] Example 21 was repeated with reduced loading of KOH (100 mmolinstead of 300 mmol) and the vessel was charged with 1.20 MPa syngas(H₂/CO=66%/34%) instead of 0.767 CO. On heating the solution to 140° C.,the pressure increased to 2.0 MPa. The gas analysis after 60 minutes wasas follows: H₂=96.1%, CO₂=0.2%, CO<50 ppm. Note that with an equivalentamount of (100 mmol) KHCO₂ in Example 25, the corresponding reactiontime was 11 minutes. These data showed that the reaction was faster withpreformed KHCO₂. Also, a comparison of the reaction time data in Example21 in which 300 mmol KOH was used and a reaction time of 21 minutesshowed that the reaction was also dependent on base concentration.

[0065] Thus, while we described what are the preferred embodiments ofthe present invention, further changes and modifications can be made bythose skilled in the art without departing from the true spirit of theinvention, and it is intended to include all such changes andmodifications as come within the scope of the claims set forth below.

1. A process for catalytic production of a hydrogen feed whichcomprises: providing a hydrogen feed; and exposing said hydrogen feed toa catalyst which promotes a water-gas-shift reaction in a liquid phase.2. The process of claim 1, wherein said hydrogen feed is provided bysteam reforming, oxidation of methanol, oxidation of methane, oxidationof biomass, coal gasification or gasification of organic wastes,plastics wastes farm wastes or wood chips
 3. The process of claim 1wherein said exposing step is conducted in a temperature range fromabout 80° C. to about 150° C.
 4. The process of claim 1, wherein formateis formed in a base-catalyzed water-gas-shift reaction.
 5. The processof claim 4, wherein said water-gas-shift reaction is conducted in thepresence of a base added in an effective amount to promote formateformation.
 6. The process of claim 5, wherein said exposing step isconducted at a pH greater than
 8. 7. The process of claim 5, whereinsaid base is selected from hydroxides, alkoxides, carbonates,bicarbonates of lithium, sodium, potassium or cesium, amines having C₁to C₄ or mixtures thereof.
 8. The process of claim 1, wherein saidcatalyst is a homogenous transition metal complex.
 9. The process ofclaim 8, wherein said transition metal is selected from the groupconsisting of Ru, Ni, Rh, Pt, Co, Cu, Pd, Ir and Fe.
 10. The process ofclaim 8, wherein said catalyst is a transition metal coupled to at leastone N-donor ligand.
 11. The process of claim 10, wherein said N-donorligand is selected from 2,2′-dipyridyl, sodium salt of ethylenediaminetetraacetic acid, ethylenediamine, 1,10-phenanthroline, 4,4′-dipyridyl,1,4,8,11-tetraazacyclotetradecane,N,N-Bis(2-hydroxybenzyl)ethylenediamine H₄, or mixtures thereof.
 12. Theprocess of claim 1, wherein said liquid phase is water, methanol, glyme,polyglycol, other alcohols from C₂ to C₁₀ or ethers from C₂ to C₁₀, andmixtures thereof.
 13. The process of claim 1, wherein said hydrogen feedhas a CO concentration in an amount from about 50 ppm to less than about20 ppm.
 14. A process for reducing CO content of a hydrogen feed for usein a proton exchange membrane fuel cell, said process comprisingproducing said hydrogen feed from formate in a liquid phase in thepresence of a formate decomposition catalyst.
 15. The process of claim14, wherein said process for producing hydrogen feed from formate isconducted in a temperate range from about 80° C. to about 150° C. 16.The process of claim 15, wherein said formate is selected from formatesof sodium, potassium, lithium and cesium.
 17. The process of claim 14,wherein said liquid phase is selected from water, methanol, glyme,polyglycol, other alcohols from C₂ to C₁₀ or ethers from C₂ to C₁₀, andmixtures thereof.
 18. The process of claim 14, wherein said formate isgenerated from CO and hydroxide in a basic solution wherein the processis a water-gas-shift reaction.
 19. The process of claim 18, wherein saidwater-gas-shift reaction comprises the steps of: (a) producing formatefrom CO and water; and (b) decomposing formate in the presence of waterto form said hydrogen feed and carbon dioxide.
 20. The process of claim14, wherein said formate decomposition catalyst is a homogenous metalcomplex.
 21. The process of claim 20, wherein said homogenous metalcomplex is a transition metal complex having a metal selected from groupVIII A.
 22. The process of claim 21, wherein said metal is selected fromthe group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt and Cu. 23.The process of claim 21, wherein said transition metal complex isselected from the group consisting of RuCl₃.xH₂O, Ru₃(CO)₁₂, NiCl₂.6H₂O,RhCl₃.3H₂O, CoCl₂, K₂PtCl₄, FeCl₂, Ru(CO)₅, Ni(CO)₄, Rh₆(CO)₁₆,Co₂(CO)₈, [Pt(CO)(Cl₂)]₂ and mixtures thereof.
 24. The process of claim23, wherein said transition metal complex is in the presence of2,2′-dipyridyl.
 25. The process of claim 14, wherein said hydrogen feedcontains an amount of CO from about 50 ppm to less than about 20 ppm.26. A process for the production of a hydrogen rich gas from a gasstream including CO, H₂O, H₂ and CH₃OH which comprises oxidizing CO toCO₂ in the presence of a liquid-phase homogenous catalytic system. 27.The process of claim 24, wherein said homogenous catalytic system is ametal complex coupled to at least one N-donor ligand.
 28. A process forcatalytic production of a hydrogen feed which comprises: providing ahydrogen feed; and exposing said hydrogen feed to a homogenous catalystwhich promotes a water-gas-shift reaction in a liquid phase at atemperature from about 80° C. to about 150° C.